What was the formal name of the Soviet offensive launched against Japan in August 1945?

The formal name of the Soviet offensive launched against Japan in August 1945 was the Manchurian Strategic Offensive Operation.

The offensive began just after midnight on August 9, 1945, following the Soviet declaration of war against Japan. Soviet forces attacked Japanese-held Manchuria from multiple directions, including eastern, western, and northern approaches. Mongolian forces also participated alongside the Soviet military.

The campaign targeted Manchukuo, Japan's puppet state in Manchuria, and rapidly overwhelmed the Japanese Kwantung Army. Soviet forces also advanced into Inner Mongolia, northern Korea, southern Sakhalin, and the Kuril Islands during the broader Soviet-Japanese War.

English-language histories sometimes call the campaign “August Storm,” but that is a later nickname rather than the formal Soviet operational title. The timing mattered greatly: the invasion began on the same day as the Nagasaki bombing and destroyed Japanese hopes that Moscow might mediate a negotiated settlement. Historians debate the relative weight of the Soviet invasion and the atomic bombings in Japan's surrender decision.